This blog is dedicated to sharing the concept that our hands are essential to learning- that we engage the world and its wonders, sensing and creating primarily through the agency of our hands. We abandon our children to education in boredom and intellectual escapism by failing to engage their hands in learning and making.

Friday, May 04, 2012

bridge testing...

Today we tested the bridge models we'd made in wood shop. The lightest bridges were the winners, though one bridge made with an arched form reached a total over 600 lbs. before failure. The winners were chosen based on the the highest ratio of load to weight. We weighted each bridge, the lightest being 1 1/4 lb. and we used 80 lb. sand bags, buckets of gravel and rocks to gather enough weight to break the bridges. The strength of these simple forms was amazing. The photo below shows the winning bridge before being pushed to its limit at 301 lbs.

The photo at top shows an arched bridge just at the point of collapse.

2 comments:

Mario, some of the designs that were just sticks of wood, laid horizontal with some side to side joining material supported an amazing amount of weight, but only by bending to extremes that would have been useless in bridges. The simple truss design shown in the bottom photo was winner on all counts. It supported 301 lbs without dramatic distortion and weighed 1 1/4 lb., less than half the weight of some others. All of the bridges surprised me except for one which tipped over from being poorly supported at the ends. I saw that coming.

About Me

I have been a self-employed woodworker in Eureka Springs, Arkansas since 1976. I live with my wife Jean on a wooded hillside overlooking our beautiful historic community.
In addition to work in my wood shop, I teach children at the Clear Spring School in a program called "The Wisdom of the Hands." My 10th and 11th books, Tiny Boxes by Taunton Press and Making Classic Toys that Teach were published in November 2016. My most recent book is The Box Maker's Guitar Book published in 2017. I also write for Fine Woodworking, Woodcraft and other woodworking magazines.
My resume can be downloaded at
www.dougstowe.com/resume.doc